Assessing Models for Pacific Absolute Plate and Plume Motions

Abstract

Absolute plate motion (APM) models derived from hot spot trails must satisfy trail geometries, ages, and paleolatitudes, which requires modeling explicit plume motions. Models lacking plume motions or derived independently from seamounts must also fit these data, provided the implicit plume motions are geodynamically reasonable. We evaluate eight Pacific APM models; three have explicitly modeled plume motions. Seven derive from seamount age progressions; one is a geodynamic model driven by slab pull and ridge push. Using the long‐lived Hawaii‐Emperor and Louisville chains, we derive implicit motions of Hawaii and Louisville plumes for models lacking explicit estimates and compare them with observed paleolatitudes. Inferred plume motions are plausible given rheological constraints on mantle flow, but rates vary considerably and not all models fit the data well. One potential endmember model predicts no APM direction change at 50 Ma, which best explains trails and paleolatitudes, minimizes predicted rotation of Pacific‐Farallon ridge and assumes no true polar motion, yet its implicit plume drift is inconsistent with global circulation models. Alternatively, a global moving hot spot model yields acceptable fits to geometry and ages, implies a major APM change at 50 Ma, but requires significant true polar wander to explain observed paleolatitudes. The inherent inconsistency between age progressions and paleolatitudes may be reconciled by true polar wander, yet questions remain about the accuracy of age progressions for older sections of the Emperor and Louisville chains, the independent geologic evidence for an APM change at 50 Ma, and the uniqueness and relevance of true polar wander estimates.